A prospective study by researchers from the Harvard School of Public Health (HSPH) has found that obesity and smoking are strongly associated with a greater risk of erectile dysfunction (ED). Meanwhile, regular physical activity appeared to have a significant impact on lowering the risk of ED. This is the first large-scale prospective study to examine the links between ED and smoking, obesity, alcohol and a sedentary lifestyle. The study will appear in the July 2006 issue of The Journal of Urology.

The researchers, led by Constance Bacon, a former post-doctoral fellow at HSPH, and Eric Rimm, associate professor of epidemiology and nutrition at HSPH, surveyed 22,086 healthy subjects between the ages of 40 and 75 from the Health Professionals Follow-up Study who reported good or very good erectile function and no major chronic disease before 1986. Among the participants, 17.7 percent (3,905) reported new onset of ED between 1986 and 2000. The researchers adjusted the results to take into account those with and without prostate cancer during the follow-up period, since prostate cancer treatments, such as radiation or surgery, may lead to ED.

The results showed that both smoking and obesity were associated with a higher risk of the development of ED among previously healthy men with good erectile function. The researchers also found that regular physical activity showed a strong inverse association with ED risk. "We found a 2.5-fold difference in risk of ED when we compared obese men who did little exercise with men who were not overweight and averaged 30 minutes of vigorous exercise a day. (Obesity was defined as a body mass index of more than 30 kilograms in weight divided by the square of height in meters.) For men younger than 55 there was a 4-fold difference in risk for the same comparison," said Rimm. Alcohol consumption did not increase the risk of ED. In general, men without prostate cancer showed stronger associations with these lifestyle factors than those with prostate cancer.

These results suggest that ED and coronary heart disease may share many of the same risk factors. Rimm said the results should encourage men to follow a more healthy lifestyle. "Many men may choose not to change to a healthier lifestyle, which includes exercise and a prudent diet, because they perceive heart disease as something that may only develop decades in the future. Hopefully, these results will help to motivate men to adopt a more active lifestyle to avoid a problem which may be more immediate," he said.

(The Health Professionals Follow-Up Study was launched in 1986 to examine diet and chronic disease among male health professionals in the U.S.)